JCW lacking in power questions. Please give me all of your ideas. - North American Motoring

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JCW lacking in power questions. Please give me all of your ideas.

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Old 02-12-2017, 07:51 AM
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LOWbikes4130 LOWbikes4130 is offline
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JCW lacking in power questions. Please give me all of your ideas.

So here is the situation.

I have a 2006 R52 JCW that I bought last year. It had no modifications, but had some front end repair paint. No known cause of accident anywhere.

The car ran great. Over the last 6 months, I have replaced the whole pulley system (ATI superdamper, new int pulley, new tensioner assy, 17% SC pulley, new serp belt). I have also fixed all fluid leaks, and some other small things.

So, ever since I bought it it has had an electric cut at around 5500rpm. The car feels like it has gobs of power, but it's also the newest car I've ever owned, so taken with a grain of salt. At around 5500rpm, my gauges flicker and reset (needles drop and pop back up), my radio cuts for a second, power steering becomes very heavy and resets, and if my heated seats are running, they turn off. This happens whether the headlights are on or off, and also when all electronics are on or off.

At first I figured it was belt slippage from the worn tensioner, so I replaced everything.

I have never had charging issues, so I skipped the alternator for now.


I didn't think it really was a big deal until last night having some fun on the freeway, I 50mph roll raced my buddies 2006 Mini Justa, and at 90mph was only a half a car length in front of him, and raced a stock gen 1 miata and didn't pull away from him at all. This tells me I'm also making [email protected]&# for power right now.

I've checked my bypass valve, which has good spring tension still, and my battery terminals, which are both tight and the ground is good, and also checked the engine ground strap at the passenger motor mount, which has almost no resistance flowing through it. I have not checked for boost leaks yet, but have bought a boost gauge, just need to install it.

Oh, and my power band from around 1500rpm to around 3500rpm in 2nd-6th gear are all very lacking.

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Old 02-12-2017, 10:27 AM
w00ht w00ht is offline
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The problem you describe is electrical, thats why the dash and radio reset and the power assisted steering stops working momentarily. In my experience, random electrical issues usually lead back to a faulty ground somewhere. Maybe something wasn't hooked back up properly when the shop took the front end apart to paint it. I'd spend a little bit of time locating all of the grounding points and ensuring the cables connected to them were in good working order by checking their resistance with an ohmmeter before spending any more money swapping parts.
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Old 02-12-2017, 04:47 PM
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ItsmeWayne ItsmeWayne is offline
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It can also be from a defective battery, that drops the voltage and then comes back. If the battery is older than three years, try a new ne that is high quality, as these have sensitive electrical systems.
Some fuses and relays can also be an issue.
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Old 02-13-2017, 06:57 AM
Racingguy04 Racingguy04 is offline
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I agree, start with the battery, if that doesn't fix it, I'd check the compression. If you're struggling to have power in all gears, you might be in need of ring or head work.
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Old 02-13-2017, 11:05 AM
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ItsmeWayne ItsmeWayne is offline
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Low power on a S model can also mean the vibration dampener on the crank, can be bad, This will cause many issues, including low power(due to supercharger stalling), battery drain (slipping Vibration dampener, so alternator does not charge battery), Overheating (usually in summer), AC does not work (because belt stalls when it is turned on) and several other things can come from this.
It may look good, but still totally shot. I have had this happen twice. If you can wag the part of the pulley on the crank, or if you can see wear, where it is hitting the engine, the dampener is toast. The good thing here is, it will fix a bunch of car ills that you are experiencing.
I hope this helps in your quest for power!
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Old 02-15-2017, 10:12 AM
Derek86 Derek86 is offline
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Having owned a 1.6 NA Miata, if you can't easily beat one you are way down on power.

The electrical cutout at a specific RPM is weird. Are you sure it is specific and not a range? If everything is resetting, that would indicate to me the car thinks the entire ignition is turning off. So what could be causing that? And then the serious lack of power to boot.

You've got a lot of diagnostics ahead of you, the belt/pulley system seems like a good place to start. Compression and leak down.

How is your car running this poorly and not throwing any codes?
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Old 07-03-2017, 02:53 PM
shuste73 shuste73 is offline
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Hi, I'm having similar issues (minus the electrical stuff) on my '06 JCW Cabrio. Can you update us on the fix?
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